101
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Castanheira M, Pereira AS, Nicoletti AG, Pignatari ACC, Barth AL, Gales AC. First report of plasmid-mediated qnrA1 in a ciprofloxacin-resistant Escherichia coli strain in Latin America. Antimicrob Agents Chemother 2007; 51:1527-9. [PMID: 17220425 PMCID: PMC1855464 DOI: 10.1128/aac.00780-06] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Among 144 ciprofloxacin-resistant Escherichia coli isolated in Brazil, one (0.69%) QnrA1-producing isolate was detected. The qnrA1 gene was associated with ISCR1. The QnrA1 determinant was carried on a 41-kb conjugative plasmid, which also carried a FOX-type cephalosporinase encoding gene and a class 1 integron with the aadB and catB3 cassettes. This is the first report of a qnrA-carrying isolate in a Latin American country.
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Affiliation(s)
- Mariana Castanheira
- Laboratório ALERTA, Universidade Federal de São Paulo, Rua Pedro de Toledo, 781 6o Andar, São Paulo, SP, and Unidade de Microbiologia, Serviço de Patologia Clínica, Hospital de Clínicas, Porto Alegre, RS, Brazil.
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102
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Cambau E, Lascols C, Sougakoff W, Bébéar C, Bonnet R, Cavallo JD, Gutmann L, Ploy MC, Jarlier V, Soussy CJ, Robert J. Occurrence of qnrA-positive clinical isolates in French teaching hospitals during 2002-2005. Clin Microbiol Infect 2006; 12:1013-20. [PMID: 16961639 DOI: 10.1111/j.1469-0691.2006.01529.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Bacteria harbouring the novel qnrA plasmid-mediated mechanism of quinolone resistance have been described in different countries, but the frequency of their occurrence has not been investigated. In total, 1,468 clinical isolates of Enterobacteriaceae with quinolone resistance or extended-spectrum beta-lactamase (ESBL) phenotypes were collected from eight teaching hospitals in France during 2002-2005 and screened for qnrA. Overall, 28 isolates (22 Enterobacter cloacae, three Klebsiella pneumoniae, one Citrobacter freundii, one Klebsiella oxytoca and one Proteus mirabilis) were positive for qnrA, representing 1.9% of all isolates, 3.3% of ESBL-producing isolates (22% of the E. cloacae isolates) and 0% of non-ESBL-producing isolates. The prevalence of qnrA among consecutive ESBL-producing isolates in 2004 from the eight hospitals was 2.8% (18/639). Of the qnrA-positive isolates, 100% were intermediately-resistant or resistant to nalidixic acid, and 75% to ciprofloxacin. Twenty-one of the 22 qnrA-positive E. cloacae isolates were obtained from two hospitals in the Paris area, and molecular typing and plasmid content analysis showed clonal relationships for five, three and two isolates, respectively. The qnrA genetic environment was similar to that of the In36 integron. The remaining two isolates had qnrA variants (30 and 29 nucleotide differences, respectively, compared with the original sequence) and an unknown genetic environment. The ESBL gene associated with qnrA was bla(SHV-12) in most of the isolates, but bla(PER-1) and bla(SHV-2a) were found in two isolates. In France, it appears that qnrA-positive isolates are predominantly E. cloacae isolates producing SHV-12, and may be associated with the dissemination of an In36-like integron.
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Affiliation(s)
- E Cambau
- Bactériologie-Virologie-Hygiène, CHU Henri Mondor, AP-HP, Université Paris XII, Paris, France.
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103
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Song W, Lee KM, Kim HS, Kim JS, Kim J, Jeong SH, Roh KH. Clonal spread of both oxyimino-cephalosporin- and cefoxitin-resistant Klebsiella pneumoniae isolates co-producing SHV-2a and DHA-1 beta-lactamase at a burns intensive care unit. Int J Antimicrob Agents 2006; 28:520-4. [PMID: 17095195 DOI: 10.1016/j.ijantimicag.2006.07.019] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2006] [Revised: 07/27/2006] [Accepted: 07/27/2006] [Indexed: 11/19/2022]
Abstract
Over a 1-month period, a total of 16 ceftriaxone- and cefoxitin-resistant Klebsiella pneumoniae isolates were isolated from 15 patients hospitalised at a burns intensive care unit (ICU). These isolates showed negative results for extended-spectrum beta-lactamase (ESBL) by the Vitek system and were highly resistant to ceftazidime, aztreonam and cefoxitin (minimum inhibitory concentrations > or =128 microg/mL). The bla(SHV-2a) and bla(DHA-1) genes were detected by polymerase chain reaction and sequence analysis. Pulsed-field gel electrophoresis profiles of the isolates were identical. AmpC disk tests for AmpC enzymes as well as double-disk tests and Clinical and Laboratory Standards Institute (CLSI) confirmatory disk tests for ESBLs yielded positive results for all the isolates. However, only three isolates (18.8%) were shown to produce ESBL by CLSI confirmatory tests using broth microdilution. We report the first outbreak of colonisations and infections due to K. pneumoniae isolates co-producing an SHV-2a ESBL and a DHA-1 AmpC beta-lactamase in a Korean hospital, which were suggested to represent a single clonal spread at a burns ICU. In addition, this report presents problems associated with ESBL detection using broth microdilution in isolates that co-produce an ESBL and an AmpC beta-lactamase.
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Affiliation(s)
- Wonkeun Song
- Department of Laboratory Medicine, Hallym University College of Medicine, Kangnam Sacred Heart Hospital, 948-1 Daelim-dong, Youngdeungpo-gu, Seoul 150-950, South Korea.
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104
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Pai H, Seo MR, Choi TY. Association of QnrB determinants and production of extended-spectrum beta-lactamases or plasmid-mediated AmpC beta-lactamases in clinical isolates of Klebsiella pneumoniae. Antimicrob Agents Chemother 2006; 51:366-8. [PMID: 17074790 PMCID: PMC1797679 DOI: 10.1128/aac.00841-06] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Clinical isolates of Escherichia coli and Klebsiella pneumoniae producing extended-spectrum beta-lactamases or plasmid-mediated AmpC beta-lactamases were screened for qnrA and qnrB genes. QnrB was present in 54 of 54 DHA-1-producing K. pneumoniae isolates and 10 of 45 SHV-12-producing ones, suggesting that the distribution of plasmids conferring resistance to extended-spectrum cephalosporins and quinolones in clinical isolates of K. pneumoniae is widespread.
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Affiliation(s)
- Hyunjoo Pai
- Division of Infectious Diseases, College of Medicine, Hanyang University, Seoul 133-791, Korea.
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105
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Robicsek A, Jacoby GA, Hooper DC. The worldwide emergence of plasmid-mediated quinolone resistance. THE LANCET. INFECTIOUS DISEASES 2006; 6:629-40. [PMID: 17008172 DOI: 10.1016/s1473-3099(06)70599-0] [Citation(s) in RCA: 619] [Impact Index Per Article: 34.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Fluoroquinolone resistance is emerging in gram-negative pathogens worldwide. The traditional understanding that quinolone resistance is acquired only through mutation and transmitted only vertically does not entirely account for the relative ease with which resistance develops in exquisitely susceptible organisms, or for the very strong association between resistance to quinolones and to other agents. The recent discovery of plasmid-mediated horizontally transferable genes encoding quinolone resistance might shed light on these phenomena. The Qnr proteins, capable of protecting DNA gyrase from quinolones, have homologues in water-dwelling bacteria, and seem to have been in circulation for some time, having achieved global distribution in a variety of plasmid environments and bacterial genera. AAC(6')-Ib-cr, a variant aminoglycoside acetyltransferase capable of modifying ciprofloxacin and reducing its activity, seems to have emerged more recently, but might be even more prevalent than the Qnr proteins. Both mechanisms provide low-level quinolone resistance that facilitates the emergence of higher-level resistance in the presence of quinolones at therapeutic levels. Much remains to be understood about these genes, but their insidious promotion of substantial resistance, their horizontal spread, and their co-selection with other resistance elements indicate that a more cautious approach to quinolone use and a reconsideration of clinical breakpoints are needed.
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Affiliation(s)
- Ari Robicsek
- Massachusetts General Hospital, Boston, MA 02114-2696, USA
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106
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Minarini LAR, Gales AC, Darini ALC. First report of plasmid-mediated resistance to quinolones and cefotaxime in an Enterobacter cloacae strain isolated from an outpatient in Brazil. Antimicrob Agents Chemother 2006; 51:401-2. [PMID: 17060528 PMCID: PMC1797657 DOI: 10.1128/aac.00935-06] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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107
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Orlén H, Hughes D. Weak mutators can drive the evolution of fluoroquinolone resistance in Escherichia coli. Antimicrob Agents Chemother 2006; 50:3454-6. [PMID: 17005830 PMCID: PMC1610101 DOI: 10.1128/aac.00783-06] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2006] [Revised: 07/12/2006] [Accepted: 07/14/2006] [Indexed: 11/20/2022] Open
Abstract
Weak mutators are common among clinical isolates of Escherichia coli. We show that the relative mutation rate and the "evolvability of fluoroquinolone resistance" are related by a power law slope of 1.2 over 3 orders of magnitude. Thus, even weak mutators can drive the evolution of fluoroquinolone resistance under selection pressure.
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Affiliation(s)
- Hanna Orlén
- Department of Cell and Molecular Biology, Biomedical Center, Uppsala University, Uppsala, Sweden
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108
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Lavigne JP, Marchandin H, Delmas J, Bouziges N, Lecaillon E, Cavalie L, Jean-Pierre H, Bonnet R, Sotto A. qnrA in CTX-M-producing Escherichia coli isolates from France. Antimicrob Agents Chemother 2006; 50:4224-8. [PMID: 16982788 PMCID: PMC1693975 DOI: 10.1128/aac.00904-06] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
By PCR, we screened for qnr genes 112 clinical isolates of extended-spectrum beta-lactamase-producing Escherichia coli collected from hospitals in France during 2004. For the first time, 7.7% of CTX-M-producing E. coli isolates presented a plasmid-mediated resistance to quinolones. All strains harbored a qnrA gene located on a sul1-type class 1 integron with similar structure to the In36 integron.
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Affiliation(s)
- Jean-Philippe Lavigne
- Laboratoire Universitaire d'Antibiologie, UFR de Médecine, Avenue Kennedy, 30908 Nîmes Cedex 02, France
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109
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Lautenbach E, Tolomeo P, Mao X, Fishman NO, Metlay JP, Bilker WB, Nachamkin I. Duration of outpatient fecal colonization due to Escherichia coli Isolates with decreased susceptibility to fluoroquinolones: longitudinal study of patients recently discharged from the hospital. Antimicrob Agents Chemother 2006; 50:3939-43. [PMID: 16982789 PMCID: PMC1635175 DOI: 10.1128/aac.00503-06] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Among 10 subjects colonized with Escherichia coli isolates with reduced susceptibility to fluoroquinolones, the median duration of colonization following hospital discharge was 80 days (range, 8 to 172 days). Colonization was longer for isolates demonstrating organic-solvent tolerance than for isolates that were not organic-solvent tolerant (151 versus 29 days, respectively; P = 0.07) but was not associated with other resistance mechanisms, demographics, or antibiotic use.
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Affiliation(s)
- Ebbing Lautenbach
- University of Pennsylvania School of Medicine, Center for Clinical Epidemiology and Biostatistics, 825 Blockley Hall, 423 Guardian Drive, Philadelphia, PA 19104-6021, USA.
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110
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Abstract
The increased use of fluoroquinolones has led to increasing resistance to these antimicrobials, with rates of resistance that vary by both organism and geographic region. Resistance to fluoroquinolones typically arises as a result of alterations in the target enzymes (DNA gyrase and topoisomerase IV) and of changes in drug entry and efflux. Mutations are selected first in the more susceptible target: DNA gyrase, in gram-negative bacteria, or topoisomerase IV, in gram-positive bacteria. Additional mutations in the next most susceptible target, as well as in genes controlling drug accumulation, augment resistance further, so that the most-resistant isolates have mutations in several genes. Resistance to quinolones can also be mediated by plasmids that produce the Qnr protein, which protects the quinolone targets from inhibition. Qnr plasmids have been found in the United States, Europe, and East Asia. Although Qnr by itself produces only low-level resistance, its presence facilitates the selection of higher-level resistance mutations, thus contributing to the alarming increase in resistance to quinolones.
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111
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Paauw A, Fluit AC, Verhoef J, Leverstein-van Hall MA. Enterobacter cloacae outbreak and emergence of quinolone resistance gene in Dutch hospital. Emerg Infect Dis 2006; 12:807-12. [PMID: 16704842 PMCID: PMC3374434 DOI: 10.3201/eid1205.050910] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Plasmid-mediated qnrA1 is an emerging resistance trait. An outbreak of Enterobacter cloacae infections with variable susceptibility to fluoroquinolones occurred in the University Medical Center Utrecht in the Netherlands in 2002. Our investigation showed that a qnrA1 gene was present in 78 (94%) of 83 outbreak isolates and that a qnrA1-encoding plasmid transferred to other strains of the same species and other species. The earliest isolate carrying this same plasmid was isolated in 1999. qnrA1 was located in a complex integron consisting of the intI1, aadB, qacEΔ1, sul1, orf513, qnrA1, ampR, qacEΔ1, and sul1 genes that were not described previously. On the same plasmid, 2 other class 1 integrons were present. One was a new integron associated with the blaCTX-M-9 extended-spectrum β-lactamase.
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Affiliation(s)
- Armand Paauw
- Eijkman-Winkler Institute for Microbiology, Infectious Diseases and Inflammation, University Medical Center Utrecht, 3508 GA Utrecht, the Netherlands.
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112
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Toleman MA, Bennett PM, Walsh TR. ISCR elements: novel gene-capturing systems of the 21st century? Microbiol Mol Biol Rev 2006; 70:296-316. [PMID: 16760305 PMCID: PMC1489542 DOI: 10.1128/mmbr.00048-05] [Citation(s) in RCA: 438] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
"Common regions" (CRs), such as Orf513, are being increasingly linked to mega-antibiotic-resistant regions. While their overall nucleotide sequences show little identity to other mobile elements, amino acid alignments indicate that they possess the key motifs of IS91-like elements, which have been linked to the mobility ent plasmids in pathogenic Escherichia coli. Further inspection reveals that they possess an IS91-like origin of replication and termination sites (terIS), and therefore CRs probably transpose via a rolling-circle replication mechanism. Accordingly, in this review we have renamed CRs as ISCRs to give a more accurate reflection of their functional properties. The genetic context surrounding ISCRs indicates that they can procure 5' sequences via misreading of the cognate terIS, i.e., "unchecked transposition." Clinically, the most worrying aspect of ISCRs is that they are increasingly being linked with more potent examples of resistance, i.e., metallo-beta-lactamases in Pseudomonas aeruginosa and co-trimoxazole resistance in Stenotrophomonas maltophilia. Furthermore, if ISCR elements do move via "unchecked RC transposition," as has been speculated for ISCR1, then this mechanism provides antibiotic resistance genes with a highly mobile genetic vehicle that could greatly exceed the effects of previously reported mobile genetic mechanisms. It has been hypothesized that bacteria will surprise us by extending their "genetic construction kit" to procure and evince additional DNA and, therefore, antibiotic resistance genes. It appears that ISCR elements have now firmly established themselves within that regimen.
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Affiliation(s)
- Mark A Toleman
- Department of Cellular and Molecular Medicine, School of Medical Sciences, University of Bristol, Bristol BS8 1TD, UK.
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113
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Muratani T, Matsumoto T. Urinary tract infection caused by fluoroquinolone- and cephem-resistant Enterobacteriaceae. Int J Antimicrob Agents 2006; 28 Suppl 1:S10-3. [PMID: 16829056 DOI: 10.1016/j.ijantimicag.2006.05.009] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In 2001, fluoroquinolone-resistant Escherichia coli isolates emerged in Japan in patients with uncomplicated urinary tract infection (UTI), and accounted for ca. 8% of isolates. This is a worldwide occurrence as reported by the ECO.SENS study. The number of fluoroquinolone- and cephem-resistant Enterobacteriaceae isolates from patients with complicated UTI is increasing. Most cephem-resistant isolates of E. coli, Klebsiella pneumoniae and Proteus mirabilis produce extended-spectrum beta-lactamases (ESBLs). The rates of ESBL-producing Enterobacteriaceae differ between countries but there are ESBL producers in urinary Enterobacteriaceae isolates in most countries. More seriously, most nosocomial ESBL producers are also resistant to non-beta-lactams, such as the fluoroquinolones, fosfomycin and co-trimoxazole. This causes serious problems in the chemotherapy of cystitis.
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Affiliation(s)
- Tetsuro Muratani
- Department of Urology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan.
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114
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Gray KJ, Wilson LK, Phiri A, Corkill JE, French N, Hart CA. Identification and characterization of ceftriaxone resistance and extended-spectrum beta-lactamases in Malawian bacteraemic Enterobacteriaceae. J Antimicrob Chemother 2006; 57:661-5. [PMID: 16537341 DOI: 10.1093/jac/dkl037] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
OBJECTIVES To enumerate and characterize extended-spectrum beta-lactamases (ESBLs) amongst ceftriaxone-resistant coliforms in Blantyre, Malawi, where third-generation cephalosporin use is currently highly restricted. METHODS Over the period April 2004-March 2005 all ceftriaxone-resistant isolates from blood cultures were examined for the presence of ESBLs. Isoelectric focusing was performed on enzyme extracts. PCR and DNA sequencing of amplicons were used to identify the underlying genetic determinants responsible for the ESBL phenotypes. Transferability of the ESBL phenotypes was tested by conjugation to a susceptible Escherichia coli J53. RESULTS Enterobacteriaceae were isolated from 1191 blood cultures, of which 19 (1.6%) were ceftriaxone resistant. Ten isolates (0.7% of all isolates) demonstrated an ESBL phenotype but only eight were characterized as three isolates were from the same patient. Genotypes SHV-11 (n = 1), SHV-12 (n = 3), SHV-27 (n = 1), TEM-63 (n = 2) and CTX-M-15 (n = 1) were detected. Plasmid transfer of the ESBL resistance phenotype was successful for all the isolates. CONCLUSIONS In a clinical setting of minimal cephalosporin usage there is already a diversity of ESBL genotypes. Increased use of cephalosporins in this setting is likely to result in a rapid expansion of ESBLs and their prevalence will need to be carefully monitored.
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115
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Jacoby GA, Walsh KE, Mills DM, Walker VJ, Oh H, Robicsek A, Hooper DC. qnrB, another plasmid-mediated gene for quinolone resistance. Antimicrob Agents Chemother 2006; 50:1178-82. [PMID: 16569827 PMCID: PMC1426915 DOI: 10.1128/aac.50.4.1178-1182.2006] [Citation(s) in RCA: 291] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A novel plasmid-mediated quinolone resistance gene, qnrB, has been discovered in a plasmid encoding the CTX-M-15 beta-lactamase from a Klebsiella pneumoniae strain isolated in South India. It has less than 40% amino acid identity with the original qnr (now qnrA) gene or with the recently described qnrS but, like them, codes for a protein belonging to the pentapeptide repeat family. Strains with qnrB demonstrated low-level resistance to all quinolones tested. The gene has been cloned in an expression vector attaching a polyhistidine tag, which facilitated purification to >or=95% homogeneity. As little as 5 pM of QnrB-His6 protected purified DNA gyrase against inhibition by 2 microg/ml (6 microM) ciprofloxacin. With a PCR assay qnrB has been detected in Citrobacter koseri, Enterobacter cloacae, and Escherichia coli isolates from the United States, linked to SHV-12 beta-lactamase and coding for a product differing in five amino acids from the Indian (now QnrB1) variety. The qnrB gene has been found near Orf1005 in some, but not all, plasmids and in association with open reading frames matching known chromosomal genes, suggesting that it too was acquired by plasmids from an as-yet-unknown bacterial source.
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116
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Hong SJ, Lee CH, Wang JH, Song W, Jung SH. Clinical Characteristics of Extended-spectrum β-lactamase Producing Shigella sonnei Infection Outbreaked in Chungju Area. Ann Lab Med 2006; 26:168-73. [DOI: 10.3343/kjlm.2006.26.3.168] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Affiliation(s)
- Seong Jin Hong
- Department of Pediatrics, Konkuk University College of Medicine, Chungju, Korea
| | - Chang Hoon Lee
- Department of Laboratory Medicine, Konkuk University College of Medicine, Chungju, Korea
| | - Jun Ho Wang
- Department of Internal Medicine, Konkuk University College of Medicine, Chungju, Korea
| | - Wonkeun Song
- Laboratory Medicine, Hallym University College of Medicine, Seoul, Korea
| | - Suk Hoon Jung
- Laboratory Medicine, Kosin University College of Medicine, Busan, Korea
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117
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Petersen A, Christensen JP, Kuhnert P, Bisgaard M, Olsen JE. Vertical transmission of a fluoroquinolone-resistant Escherichia coli within an integrated broiler operation. Vet Microbiol 2006; 116:120-8. [PMID: 16650662 DOI: 10.1016/j.vetmic.2006.03.015] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2005] [Revised: 03/18/2006] [Accepted: 03/24/2006] [Indexed: 11/24/2022]
Abstract
The epidemiology of an enrofloxacin-resistant Escherichia coli clone was investigated during two separate outbreaks of colibacillosis in the Danish broiler production. In total five flocks were reported affected by the outbreaks. Recorded first-week mortalities were in the range of 1.7-12.7%. The clone was first isolated from dead broilers and subsequently demonstrated in samples from associated hatchers and the parent flock with its embryonated eggs, suggesting a vertical transmission from the parents. The second outbreak involved two broiler flocks unrelated to the affected flocks from the first outbreak. However, the clone could not be demonstrated in the associated parent flock. Furthermore, samplings from grand-parent flocks were negative for the outbreak clone. The clonality was evaluated by plasmid profiling and pulsed-field gel electrophoresis. None of the recognized virulence factors were demonstrated in the outbreak clone by microarray and PCR assay. The molecular background for the fluoroquinolone-resistance was investigated and point mutations in gyrA and parC leading to amino-acid substitutions in quinolone-resistance determining regions of GyrA and ParC were demonstrated. Vertical transmission of enrofloxacin-resistant E. coli from healthy parents resulting in high first-week mortality in the offspring illustrates the potential of the emergence and spreading of fluoroquinolone-resistant bacteria in animal husbandry, even though the use of fluoroquinolones is restricted.
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Affiliation(s)
- Andreas Petersen
- The Royal Veterinary & Agricultural University, Department of Veterinary Pathobiology, Stigbøjlen 4, 1870 Frederiksberg C, Denmark.
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118
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Rodríguez-Martínez JM, Velasco C, Pascual A, García I, Martínez-Martínez L. Correlation of quinolone resistance levels and differences in basal and quinolone-induced expression from three qnrA-containing plasmids. Clin Microbiol Infect 2006; 12:440-5. [PMID: 16643520 DOI: 10.1111/j.1469-0691.2006.01389.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
This study investigated the effect of copy number and transcriptional level of the qnrA gene on plasmid-mediated quinolone resistance, and the effect of quinolones on qnrA expression, in three clinical isolates of Klebsiella pneumoniae and the corresponding Escherichia coli transconjugants. The copy number of plasmids containing qnrA was analysed and transcriptional studies were performed on transconjugants grown in the presence or absence of ciprofloxacin or moxifloxacin. None of the three clinical isolates was porin-deficient. One isolate contained a mutation in the quinolone resistance-determining region of the gyrA gene (Ser83Phe), but no gyrA mutations were present in the other two isolates, and no mutations were found in parC. Differences in qnrA copy number were observed in K. pneumoniae, but not in the corresponding E. coli transconjugants, although the qnrA gene was located in plasmids with similar mobility and Southern blot RFLP pattern. Differences in qnrA transcription, both at the basal level and following induction by quinolones, were observed among transconjugants. Expression of the qnrA gene correlated well with the level of quinolone (ciprofloxacin and moxifloxacin) resistance in E. coli transconjugants. These data suggest that the main factor determining the resistance level in the transconjugants analysed was the different levels of qnrA expression.
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Affiliation(s)
- J M Rodríguez-Martínez
- Department of Microbiology, School of Medicine, University of Seville, C/Sanchez Pizjuan s/n, 41009 Seville, Spain.
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119
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Honoré S, Lascols C, Malin D, Targaouchi R, Cattoir V, Legrand P, Soussy CJ, Cambau E. [Investigation of the new QNR-based mechanism of quinolone resistance among enterobacterial strains isolated in Henri-Mondor hospital 2002-2005]. ACTA ACUST UNITED AC 2006; 54:270-9. [PMID: 16473479 DOI: 10.1016/j.patbio.2005.11.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2005] [Accepted: 11/21/2005] [Indexed: 11/23/2022]
Abstract
AIM OF THE STUDY To assess the prevalence of the novel plasmid-mediated resistance to quinolones in enterobacteria isolated in our hospital. MATERIALS AND METHODS We have screened 737 enterobacterial strains isolated in Henri-Mondor hospital between 2002 and 2005 for the presence of the qnr gene by PCR using specific primers. Among them, 282 had a phenotype in concordance with extended spectrum betalactamase (ESBL). Qnr-positive strains were phenotypically and genetically characterized, and epidemiological link between the cases was investigated. RESULTS Five qnr+ strains were described. The global prevalence was 0.7% but 5/282 among ESBL producing strains and 0/437 among quinolone-resistant enterobacteria non producing ESBL. The sequences of the PCR products were identical to qnrA in the environment of the integron In36. All the strains harboured also the ESBL SHV-12 gene. Transfer of qnr by conjugation raised quinolone MICs from 2 to 24 times. However clinical strains harboured a higher level of quinolone resistance and harboured also DNA gyrase and topoisomerase IV mutations. Two strains were epidemiologically related by molecular typing and contact tracing revealed that the patients have been previously hospitalized in the same tertiary care center. CONCLUSION We described the first investigation of qnr-positive strains in one hospital in France over 4 years. Although the qnr gene prevalence is low, nosocomial transmission is already shown and the transfer of the qnr containing integron among ESBL producing strains may predict future epidemic. Surveillance will be necessary to confirm this low prevalence rate of qnr in France.
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Affiliation(s)
- S Honoré
- Laboratoire de bactériologie-virologie-hygiène, CHU Henri-Mondor, Assistance publique-Hôpitaux de Paris, université Paris-XII, 51, avenue du maréchal-de-Lattre-de-Tassigny, 94010 Créteil cedex, France
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120
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Nordmann P. [Emergence of plasmid-mediated resistance to quinolones in Enterobacteriaceae]. PATHOLOGIE-BIOLOGIE 2006; 54:7-9. [PMID: 16376173 DOI: 10.1016/j.patbio.2005.01.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2005] [Accepted: 01/19/2005] [Indexed: 05/05/2023]
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121
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Talukder KA, Khajanchi BK, Islam MA, Islam Z, Dutta DK, Rahman M, Watanabe H, Nair GB, Sack DA. Fluoroquinolone resistance linked to both gyrA and parC mutations in the quinolone resistance-determining region of Shigella dysenteriae type 1. Curr Microbiol 2006; 52:108-11. [PMID: 16450072 DOI: 10.1007/s00284-005-0140-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2005] [Accepted: 08/01/2005] [Indexed: 11/28/2022]
Abstract
We examined the quinolone resistance-determining region (QRDR) of gyrA, gyrB, and parC of recently isolated fluoroquinolone-resistant S. dysenteriae type 1 strains from south Asia and compared data with fluoroquinolone-susceptible strains associated with previous epidemics of 1978, 1984, and 1994. In fluoroquinolone-resistant strains, double mutations (Ser83-->Leu, Asp87-->Asn or Gly) and a single mutation (Ser80-->Ile) were detected in the QRDRs of gyrA and parC, respectively.
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Affiliation(s)
- Kaisar A Talukder
- ICDDR, B: Centre for Health and Population Research, GPO Box-128, Dhaka, 1000, Bangladesh.
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122
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Abstract
Extended-spectrum beta-lactamases (ESBLs) are a rapidly evolving group of beta-lactamases which share the ability to hydrolyze third-generation cephalosporins and aztreonam yet are inhibited by clavulanic acid. Typically, they derive from genes for TEM-1, TEM-2, or SHV-1 by mutations that alter the amino acid configuration around the active site of these beta-lactamases. This extends the spectrum of beta-lactam antibiotics susceptible to hydrolysis by these enzymes. An increasing number of ESBLs not of TEM or SHV lineage have recently been described. The presence of ESBLs carries tremendous clinical significance. The ESBLs are frequently plasmid encoded. Plasmids responsible for ESBL production frequently carry genes encoding resistance to other drug classes (for example, aminoglycosides). Therefore, antibiotic options in the treatment of ESBL-producing organisms are extremely limited. Carbapenems are the treatment of choice for serious infections due to ESBL-producing organisms, yet carbapenem-resistant isolates have recently been reported. ESBL-producing organisms may appear susceptible to some extended-spectrum cephalosporins. However, treatment with such antibiotics has been associated with high failure rates. There is substantial debate as to the optimal method to prevent this occurrence. It has been proposed that cephalosporin breakpoints for the Enterobacteriaceae should be altered so that the need for ESBL detection would be obviated. At present, however, organizations such as the Clinical and Laboratory Standards Institute (formerly the National Committee for Clinical Laboratory Standards) provide guidelines for the detection of ESBLs in klebsiellae and Escherichia coli. In common to all ESBL detection methods is the general principle that the activity of extended-spectrum cephalosporins against ESBL-producing organisms will be enhanced by the presence of clavulanic acid. ESBLs represent an impressive example of the ability of gram-negative bacteria to develop new antibiotic resistance mechanisms in the face of the introduction of new antimicrobial agents.
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Affiliation(s)
- David L Paterson
- Infectious Disease Division, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA.
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123
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Rodríguez-Martinez JM, Conejo MC, Martínez-Martínez L, Cano ME, Velasco C, Pascual A. Evaluation of antimicrobial susceptibility of bacteria containing the qnr gene and FOX-5 beta-lactamase by four automated systems. Clin Microbiol Infect 2005; 11:402-4. [PMID: 15819868 DOI: 10.1111/j.1469-0691.2005.01097.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The accuracy and performance of four automated instruments (BD Phoenix, MicroScan WalkAway, VITEK-2 and Wider) were evaluated for susceptibility testing of fluoroquinolones and beta-lactams with four clinical isolates of Klebsiella pneumoniae and the corresponding Escherichia coli transconjugants containing a plasmid carrying the qnr gene and coding for FOX-5 production. No major or very major errors were detected with the MicroScan system. Many of the minor errors for both quinolones and beta-lactams clustered around the intermediate breakpoints.
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Mooij MJ, Schouten I, Vos G, Van Belkum A, Vandenbroucke-Grauls CMJE, Savelkoul PHM, Schultsz C. Class 1 integrons in ciprofloxacin-resistant Escherichia coli strains from two Dutch hospitals. Clin Microbiol Infect 2005; 11:898-902. [PMID: 16216105 DOI: 10.1111/j.1469-0691.2005.01259.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A significant increase in the isolation frequency of ciprofloxacin-resistant Escherichia coli was observed in the haematology departments of two university hospitals in The Netherlands. Amplified fragment length polymorphism analysis revealed that this increase was not caused by the emergence of unique ciprofloxacin-resistant clones. Determination of the presence of class 1 integrons indicated that 81% of the ciprofloxacin-resistant isolates contained an intI1 gene, compared with 11% of the ciprofloxacin-susceptible isolates (p<0.0001). The quinolone resistance gene qnrA was not present in any of the integrons characterised and could not be detected using dot-blot hybridisation of total DNA. In addition, conjugation experiments showed that ciprofloxacin resistance was not co-transferred with class 1 integrons. Ciprofloxacin-resistant isolates harboured mutations in the gyrA gene, which are known to encode ciprofloxacin resistance. In conclusion, an association was observed between ciprofloxacin resistance and the presence of class 1 integrons, which could not be explained by the currently known genetic determinants of quinolone resistance.
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Affiliation(s)
- M J Mooij
- Department of Medical Microbiology and Infection Control, VU University Medical Center, Amsterdam, The Netherlands
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125
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Corkill JE, Anson JJ, Hart CA. High prevalence of the plasmid-mediated quinolone resistance determinant qnrA in multidrug-resistant Enterobacteriaceae from blood cultures in Liverpool, UK. J Antimicrob Chemother 2005; 56:1115-7. [PMID: 16260446 DOI: 10.1093/jac/dki388] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVES To determine the prevalence of the plasmid-mediated quinolone resistance qnrA gene in a selected collection of blood culture isolates of Enterobacteriaceae resistant to both ciprofloxacin and cefotaxime. METHODS Over a 29 month period, a total of 47 non-repetitive isolates of Enterobacteriaceae resistant to both ciprofloxacin and cefotaxime were identified. Isolates were screened for the presence of the qnrA gene, class I integrons and bla(ESBL) by PCR. Transferability was examined by conjugation with the sodium azide-resistant Escherichia coli J53. All qnrA-positive isolates were examined for DNA-relatedness by PFGE. RESULTS A total of 15 of the 47 test isolates (32%) were positive for the qnrA gene, and included single isolates of E. coli and Citrobacter freundii, 4 Klebsiella pneumoniae and 9 Enterobacter cloacae. All 15 qnrA-positive isolates carried class 1 integrons, and 11 the extended-spectrum beta-lactamase gene bla(SHV-12). By PFGE two K. pneumoniae and three E. cloacae, respectively, were considered clonally but not temporally related. Plasmid transfer of quinolone resistance was only achieved with single isolates of K. pneumoniae and E. cloacae. Both plasmids carried class 1 integrons with a pSAL-1-like gene cassette arrangement intl1-aadA2-qacEDelta-sul1. CONCLUSIONS In this selected group of ciprofloxacin- and cefotaxime-resistant bacteria, carriage of the qnrA gene was high (32%). This compares with <2.0% as demonstrated in worldwide studies of laboratory collections of ciprofloxacin-resistant bacteria. The majority of qnrA-positive isolates in our study originated from high-dependency care units within our hospital, but were shown not to be clonal by PFGE. This is the first report of qnrA-positive Enterobacteriaceae in the United Kingdom.
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Affiliation(s)
- John E Corkill
- Department of Medical Microbiology, Royal Liverpool University Hospital, Liverpool L7 8XP, UK.
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Choi SH, Woo JH, Lee JE, Park SJ, Choo EJ, Kwak YG, Kim MN, Choi MS, Lee NY, Lee BK, Kim NJ, Jeong JY, Ryu J, Kim YS. Increasing incidence of quinolone resistance in human non-typhoid Salmonella enterica isolates in Korea and mechanisms involved in quinolone resistance. J Antimicrob Chemother 2005; 56:1111-4. [PMID: 16244086 DOI: 10.1093/jac/dki369] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
OBJECTIVES We investigated the trends of nalidixic acid resistance in human non-typhoid Salmonella enterica in a Korean population, and examined some possible mechanisms involved in this resistance. METHODS A total of 261 clinical strains were tested. For all strains, the MICs of nalidixic acid were determined. Nalidixic acid-resistant strains underwent further analysis, including determination of MICs of other antibiotics, mutation analysis within the topoisomerase genes, organic solvent tolerance test, western blotting for AcrA, marOR mutation analysis, ciprofloxacin accumulation test, and PCR for the qnr gene. The clonal relationships of Salmonella strains were examined by random amplified polymorphic DNA analysis. RESULTS The incidence of nalidixic acid resistance increased from 1.8% in 1995-96 to 21.8% in 2000-02. The resistance rate was higher in S. enterica serotype Enteritidis (21.6%) than in serotype Typhimurium (12.1%). The nalidixic acid resistance rates in Salmonella Enteritidis varied according to the phage type (PT) and Salmonella Enteritidis PT 1 was most commonly associated with resistance to nalidixic acid. Several cases of clonal spread, especially by Salmonella Enteritidis PT 1, were identified. Of the 46 nalidixic acid-resistant strains, 43 had single mutations in the gyrA gene. Four strains were organic solvent-tolerant and were associated with decreased ciprofloxacin accumulation; three of these showed increased expression of AcrA and had novel mutations in marOR (84L). The qnr gene was not identified. CONCLUSIONS Recently, the rate of nalidixic acid resistance in Korean clinical Salmonella strains markedly increased and it was partly due to the clonal spread of Salmonella Enteritidis, especially PT 1. The main mechanism of nalidixic acid resistance was a mutation in the gyrA region.
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Affiliation(s)
- Sang-Ho Choi
- Division of Infectious Diseases, Asan Medical Center, University of Ulsan College of Medicine, Songpa-gu, Seoul, Republic of Korea
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Poirel L, Rodriguez-Martinez JM, Mammeri H, Liard A, Nordmann P. Origin of plasmid-mediated quinolone resistance determinant QnrA. Antimicrob Agents Chemother 2005; 49:3523-5. [PMID: 16048974 PMCID: PMC1196254 DOI: 10.1128/aac.49.8.3523-3525.2005] [Citation(s) in RCA: 260] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Plasmid-mediated resistance to quinolones is increasingly reported in studies of Enterobacteriaceae. Using a PCR-based strategy, a series of gram-negative species were screened for qnrA-like genes. Shewanella algae, an environmental species from marine and fresh water, was identified as its reservoir. This is a one of the very few examples of progenitor identification of an acquired antibiotic resistance gene.
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Affiliation(s)
- Laurent Poirel
- Service de Bactériologie-Virologie, Hôpital de Bicêtre, 78, rue du General Leclerc, 94275 Le Kremlin-Bicêtre, France
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128
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Martinez M, McDermott P, Walker R. Pharmacology of the fluoroquinolones: a perspective for the use in domestic animals. Vet J 2005; 172:10-28. [PMID: 16154368 DOI: 10.1016/j.tvjl.2005.07.010] [Citation(s) in RCA: 233] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The fluoroquinolones are a class of compounds that comprise a large and expanding group of synthetic antimicrobial agents. Structurally, all fluoroquinolones contain a fluorine molecule at the 6-position of the basic quinolone nucleus. Despite the basic similarity in the core structure of these molecules, their physicochemical properties, pharmacokinetic characteristics and microbial activities can vary markedly across compounds. The first of the fluoroquinolones approved for use in animals, enrofloxacin, was approved in the late 1980s. Since then, five other fluoroquinolones have been marketed for use in animals in the United States, with others currently under investigation. This review focuses on the use of fluoroquinolones within veterinary medicine, providing an overview of the structure-activity relationship of the various members of the group, the clinical uses of fluoroquinolones in veterinary medicine, their pharmacokinetics and potential interspecies differences, an overview of the current understanding of the pharmacokinetic/pharmacodynamic relationships associated with fluoroquinolones, a summary of toxicities that have been associated with this class of compounds, their use in both in human and veterinary species, mechanisms associated with the development of microbial resistance to the fluoroquinolones, and a discussion of fluoroquinolone dose optimization. Although the review contains a large body of basic research information, it is intended that the contents of this review have relevance to both the research scientist and the veterinary medical practitioner.
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Affiliation(s)
- Marilyn Martinez
- US Food and Drug Administration, Center for Veterinary Medicine, Office of New Animal Drug Evaluation, Rockville, MD 20855, USA
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129
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Poirel L, Van De Loo M, Mammeri H, Nordmann P. Association of plasmid-mediated quinolone resistance with extended-spectrum beta-lactamase VEB-1. Antimicrob Agents Chemother 2005; 49:3091-4. [PMID: 15980408 PMCID: PMC1168703 DOI: 10.1128/aac.49.7.3091-3094.2005] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Association of the plasmid-mediated quinolone resistance determinant QnrA and the bla(VEB-1) gene was identified in a single Enterobacter cloacae isolate from K.-Bicêtre, France, and in 11 out of 23 bla(VEB-1)-positive enterobacterial isolates from Bangkok, Thailand. This result may explain in part the association between quinolone and extended-spectrum beta-lactam resistance.
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Affiliation(s)
- Laurent Poirel
- Service de Bactériologie-Virologie, Hôpital de Bicêtre, Assistance Publique/Hôpitaux de Paris, Faculté de Médecine Paris-Sud, Université Paris XI, Le Kremlin-Bicêtre, France
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130
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Jeong JY, Yoon HJ, Kim ES, Lee Y, Choi SH, Kim NJ, Woo JH, Kim YS. Detection of qnr in clinical isolates of Escherichia coli from Korea. Antimicrob Agents Chemother 2005; 49:2522-4. [PMID: 15917562 PMCID: PMC1140518 DOI: 10.1128/aac.49.6.2522-2524.2005] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
qnr was detected in 2 of 260 Escherichia coli clinical isolates collected from a Korean hospital during the period 2001 to 2003. The two strains were not clonally related. qnr was located in In4 family class 1 integrons of original structure, downstream of orf513 and upstream from another resistance gene (dfrA3b) and a gene of unknown function (orf105). Transfer of the qnr determinant by conjugation could be detected from only one strain.
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Affiliation(s)
- Jin-Yong Jeong
- Division of Infectious Diseases, Asan Medical Center and Asan Institute for Life Sciences, University of Ulsan College of Medicine, 388-1 Pungnap-dong, Songpa-gu, Seoul 138-736, Korea
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131
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Cheung TKM, Chu YW, Chu MY, Ma CH, Yung RWH, Kam KM. Plasmid-mediated resistance to ciprofloxacin and cefotaxime in clinical isolates of Salmonella enterica serotype Enteritidis in Hong Kong. J Antimicrob Chemother 2005; 56:586-9. [PMID: 16033804 DOI: 10.1093/jac/dki250] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
OBJECTIVES To characterize the genetic determinants involved in the reduced susceptibility to ciprofloxacin and cefotaxime in Salmonella enterica serotype Enteritidis clinical isolates obtained from four patients in summer 2003 in Hong Kong. METHODS Three Salmonella Enteritidis isolates from blood culture and one from stool were collected due to their increased resistance to ciprofloxacin and cefotaxime. PFGE analysis was used to investigate their genetic relatedness. Conjugation experiments were employed to show if the genetic determinants involved were plasmid-mediated. MICs of various antimicrobials were determined by VITEK 2 and Etest. Based on the susceptibility and conjugation experiment results, previously described PCR methods were employed to detect sequences homologous to qnr and bla(CTX-M) suspected to be involved in the reduced susceptibility to ciprofloxacin and cefotaxime, respectively. RESULTS PFGE analysis showed that the four Salmonella isolates were clonally unrelated. The presence of a qnr-like gene and the CTX-M allele bla(CTX-M-14) on four different transferable plasmids harboured by the four isolates was confirmed. CONCLUSIONS This is the first report of transferable fluoroquinolone resistance due to a new qnr allele, which appeared to be linked to bla(CTX-M-14), in isolates of Salmonella Enteritidis in Hong Kong.
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Affiliation(s)
- Terence Kin Man Cheung
- Microbiology Division, Public Health Laboratory Services Branch, Centre for Health Protection, Department of Health, Hong Kong SAR, China
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132
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Saga T, Kaku M, Onodera Y, Yamachika S, Sato K, Takase H. Vibrio parahaemolyticus chromosomal qnr homologue VPA0095: demonstration by transformation with a mutated gene of its potential to reduce quinolone susceptibility in Escherichia coli. Antimicrob Agents Chemother 2005; 49:2144-5. [PMID: 15855551 PMCID: PMC1087611 DOI: 10.1128/aac.49.5.2144-2145.2005] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Nordmann P, Poirel L. Emergence of plasmid-mediated resistance to quinolones in Enterobacteriaceae. J Antimicrob Chemother 2005; 56:463-9. [PMID: 16020539 DOI: 10.1093/jac/dki245] [Citation(s) in RCA: 292] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Although quinolone resistance results mostly from chromosomal mutations in Enterobacteriaceae, it may also be mediated by plasmid-encoded Qnr determinants. Qnr proteins protect DNA from quinolone binding and compromise the efficacy of quinolones such as nalidixic acid. Qnr proteins (QnrA-like, QnrB and QnrS) have been identified worldwide with a quite high prevalence among Asian isolates with a frequent association with clavulanic acid inhibited expanded-spectrum beta-lactamases and plasmid-mediated cephalosporinases. The qnrA genes are embedded in complex sul1-type integrons. A very recent identification of the origin of QnrA determinants in the water-borne species Shewanella algae underlines the role of the environment as a reservoir for this emerging threat. It may help to determine the location of in vivo transfer of qnrA genes. Further analysis of the role (if any) of quinolones for enhancing this gene transfer may be conducted. This could prevent the spread, if still possible, of this novel antibiotic resistance mechanism.
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Affiliation(s)
- Patrice Nordmann
- Service de Bactériologie-Virologie, Hôpital de Bicêtre, Assistance Publique/Hôpitaux de Paris, Faculté de Médecine Paris-Sud, Université Paris Sud, 78 rue du Général Leclerc, 94275, K.-Bicêtre, France.
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Schwaber MJ, Navon-Venezia S, Schwartz D, Carmeli Y. High levels of antimicrobial coresistance among extended-spectrum-beta-lactamase-producing Enterobacteriaceae. Antimicrob Agents Chemother 2005; 49:2137-9. [PMID: 15855548 PMCID: PMC1087677 DOI: 10.1128/aac.49.5.2137-2139.2005] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We compared the susceptibility of 312 extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae isolates with that of 1,216 ESBL nonproducers. Of ESBL producers, 25% were susceptible to gentamicin, 30% to trimethoprim-sulfamethoxazole, 41% to ciprofloxacin, and 60% to piperacillin-tazobactam. ESBL nonproducers were more often susceptible to these agents. ESBL-producing Enterobacteriaceae represent a major source of resistance to various antibiotics.
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Affiliation(s)
- Mitchell J Schwaber
- Division of Epidemiology, Tel Aviv Sourasky Medical Center, 6 Weizmann St., Tel Aviv 64239, Israel.
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135
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Nazic H, Poirel L, Nordmann P. Further identification of plasmid-mediated quinolone resistance determinant in Enterobacteriaceae in Turkey. Antimicrob Agents Chemother 2005; 49:2146-7. [PMID: 15855552 PMCID: PMC1087610 DOI: 10.1128/aac.49.5.2146-2147.2005] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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136
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Rice LB. Emerging Issues in the Management of Infections Caused by Multi-Drug-Resistant, Gram-Negative Bacilli. Surg Infect (Larchmt) 2005. [DOI: 10.1089/sur.2005.6.s2-37] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Louis B. Rice
- Louis Stokes Cleveland VA Medical Center, Cleveland, Ohio
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137
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Hegde SS, Vetting MW, Roderick SL, Mitchenall LA, Maxwell A, Takiff HE, Blanchard JS. A fluoroquinolone resistance protein from Mycobacterium tuberculosis that mimics DNA. Science 2005; 308:1480-3. [PMID: 15933203 DOI: 10.1126/science.1110699] [Citation(s) in RCA: 196] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Fluoroquinolones are gaining increasing importance in the treatment of tuberculosis. The expression of MfpA, a member of the pentapeptide repeat family of proteins from Mycobacterium tuberculosis, causes resistance to ciprofloxacin and sparfloxacin. This protein binds to DNA gyrase and inhibits its activity. Its three-dimensional structure reveals a fold, which we have named the right-handed quadrilateral beta helix, that exhibits size, shape, and electrostatic similarity to B-form DNA. This represents a form of DNA mimicry and explains both its inhibitory effect on DNA gyrase and fluoroquinolone resistance resulting from the protein's expression in vivo.
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Affiliation(s)
- Subray S Hegde
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
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138
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Abstract
Bacterial resistance to quinolones/fluoroquinolones has emerged rapidly and such resistance has traditionally been attributed to the chromosomally mediated mechanisms that alter the quinolone targets (i.e. DNA gyrase and topoisomerase IV) and/or overproduce multidrug resistance efflux pumps. However, the discovery of the plasmid-borne quinolone resistance determinant, named qnr, has substantially broadened our horizon on the molecular mechanisms of quinolone resistance. Several recent reports of Qnr or its homologues encoded by transferable plasmids in Gram-negative bacteria isolated worldwide highlight the significance of the emerging plasmid-mediated mechanism(s). This also alerts us to the potential rapid dissemination of quinolone resistance determinants. Qnr belongs to the pentapeptide repeat family and protects DNA gyrase from the action of quinolone agents including the newer fluoroquinolones. This protection interplays with chromosomal mechanisms to raise significantly the resistance levels. The qnr-bearing strains generate quinolone-resistant mutants at a much higher frequency than those qnr-free strains. Furthermore, the qnr-plasmids are integron-associated and carry multiple resistance determinants providing resistance to several classes of antimicrobials including beta-lactams and aminoglycosides. The high quinolone resistance rates in Escherichia coli are used to address issues of quinolone resistance, and possible strategies for minimising quinolone resistance are discussed.
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Affiliation(s)
- Xian-Zhi Li
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720-3202, USA.
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139
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Hopkins KL, Davies RH, Threlfall EJ. Mechanisms of quinolone resistance in Escherichia coli and Salmonella: Recent developments. Int J Antimicrob Agents 2005; 25:358-73. [PMID: 15848289 DOI: 10.1016/j.ijantimicag.2005.02.006] [Citation(s) in RCA: 374] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Fluoroquinolones are broad-spectrum antimicrobials highly effective for treatment of a variety of clinical and veterinary infections. Their antibacterial activity is due to inhibition of DNA replication. Usually resistance arises spontaneously due to point mutations that result in amino acid substitutions within the topoisomerase subunits GyrA, GyrB, ParC or ParE, decreased expression of outer membrane porins, or overexpression of multidrug efflux pumps. In addition, the recent discovery of plasmid-mediated quinolone resistance could result in horizontal transfer of fluoroquinolone resistance between strains. Acquisition of high-level resistance appears to be a multifactorial process. Care needs to taken to avoid overuse of this important class of antimicrobial in both human and veterinary medicine to prevent an increase in the occurrence of resistant zoonotic and non-zoonotic bacterial pathogens that could subsequently cause human or animal infections.
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Affiliation(s)
- Katie L Hopkins
- Antimicrobial Resistance and Molecular Epidemiology Unit, Laboratory of Enteric Pathogens, Health Protection Agency Centre for Infections, 61 Colindale Avenue, London NW9 5HT, UK.
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140
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Marcusson LL, Olofsson SK, Komp Lindgren P, Cars O, Hughes D. Mutant prevention concentrations of ciprofloxacin for urinary tract infection isolates of Escherichia coli. J Antimicrob Chemother 2005; 55:938-43. [PMID: 15860549 DOI: 10.1093/jac/dki136] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
OBJECTIVES To measure the mutant prevention concentration (MPC) of ciprofloxacin for a set of urinary tract infection (UTI) Escherichia coli isolates with different levels of susceptibility and determine whether MPC can be predicted from MIC. METHODS MPC was defined as the lowest ciprofloxacin concentration that prevented the growth of resistant colonies when 10(10) bacteria were spread on solid medium and incubated for 96 h at 37 degrees C. MIC was measured by Etest. Bacteria surviving (persisting) at MPC were isolated and quantified from agar plugs taken after 96 h. The genes hipA and hipB were amplified by PCR from persisters and sequenced. RESULTS Isolates with MICs above the NCCLS breakpoint for ciprofloxacin resistance (4 mg/L) typically have MPCs greater than 32 mg/L. Isolates with MICs below the breakpoint for ciprofloxacin susceptibility (1 mg/L) have MPCs up to 5 mg/L. MPC/MIC is approximately 16 for most susceptible isolates but there are several notable exceptions (MPC/MIC > 100). Resistant colonies arising one dilution step below MPC often had MIC > MPC. In every case tested, a proportion of cells survived (persisted), but did not grow into colonies, at MPC, without any increase in MIC. CONCLUSIONS MPCs were determined for all ciprofloxacin-susceptible isolates. MPC is not accurately predicted from MIC. Colonies selected below MPC frequently have MIC > MPC, suggesting multiple mutations. A small fraction of cells from all strains tested survived for 96 h at MPC, without any associated increase in MIC. These survivors/persisters are not hipAB mutants.
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Affiliation(s)
- Linda L Marcusson
- Department of Cell and Molecular Biology, Box 596, Biomedical Center, Uppsala University, S-751 24, Uppsala, Sweden
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141
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Rodríguez-Martínez JM. [Mechanisms of plasmid-mediated resistance to quinolones]. Enferm Infecc Microbiol Clin 2005; 23:25-31. [PMID: 15701330 DOI: 10.1157/13070406] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Quinolone resistance is caused mainly by chromosomal mutations in gram negative bacteria. In 1998, plasmid-mediated resistance to quinolones in clinical isolates was first reported in a Klebsiella pneumoniae strain. Locus qnr (quinolone resistance) was responsible of the quinolone resistance in this plasmid. qnr codes a protein whose function is protect both DNA-girase and topoisomerase IV from these antimicrobials. Moreover, qnr is located in an integron-like structure upstream of qacEDelta y sul1. A review of the information obtained in the last years about this mechanism of resistance was performed.
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142
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Hata M, Suzuki M, Matsumoto M, Takahashi M, Sato K, Ibe S, Sakae K. Cloning of a novel gene for quinolone resistance from a transferable plasmid in Shigella flexneri 2b. Antimicrob Agents Chemother 2005; 49:801-3. [PMID: 15673773 PMCID: PMC547361 DOI: 10.1128/aac.49.2.801-803.2005] [Citation(s) in RCA: 234] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A novel gene for quinolone resistance was cloned from a transferable plasmid carried by a clinical isolate of Shigella flexneri 2b that was resistant to fluoroquinolones. The plasmid conferred low-level resistance to quinolones on Escherichia coli HB101. The protein encoded by the gene showed 59% amino acid identity with Qnr.
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Affiliation(s)
- Mami Hata
- Department of Microbiology, Aichi Prefectural Institute of Public Health, 7-6 Nagare, Tsujimachi, Kita-ku, Nagoya, Aichi 462-8576, Japan.
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143
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Jonas D, Biehler K, Hartung D, Spitzmüller B, Daschner FD. Plasmid-mediated quinolone resistance in isolates obtained in german intensive care units. Antimicrob Agents Chemother 2005; 49:773-5. [PMID: 15673764 PMCID: PMC547280 DOI: 10.1128/aac.49.2.773-775.2005] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Screening of 703 isolates of Enterobacteriaceae, obtained from 34 German intensive care units (ICUs), revealed qnr-positive, integron-containing isolates of Enterobacter sp. and Citrobacter freundii from four patients in 2 German ICUs. This is one of the first reports of qnr-positive strains obtained from patients in Europe.
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Affiliation(s)
- Daniel Jonas
- Institute of Environmental Medicine and Hospital Epidemiology, University Hospital Freiburg, Hugstetter Str. 55, D-79106 Freiburg, Germany.
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144
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Mammeri H, Van De Loo M, Poirel L, Martinez-Martinez L, Nordmann P. Emergence of plasmid-mediated quinolone resistance in Escherichia coli in Europe. Antimicrob Agents Chemother 2005; 49:71-6. [PMID: 15616277 PMCID: PMC538905 DOI: 10.1128/aac.49.1.71-76.2005] [Citation(s) in RCA: 207] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Although quinolone resistance results mostly from chromosomal mutations, it may also be mediated by a plasmid-encoded qnr gene in members of the family Enterobacteriaceae. Thus, 297 nalidixic-acid resistant strains of 2,700 Escherichia coli strains that had been isolated at the Bicetre Hospital (Le Kremlin-Bicetre, France) in 2003 were screened for qnr by PCR. A single E. coli isolate that carried a ca. 180-kb conjugative plasmid encoding a qnr determinant was identified. It conferred low-level resistance to quinolones and was associated with a chromosomal mutation in subunit A of the topoisomerase II gene. The qnr gene was located on a sul1-type class 1 integron just downstream of a conserved region (CR) element (CR1) comprising the Orf513 recombinase. Promoter sequences for qnr expression overlapped the extremity of CR1, indicating the role of CR1 in the expression of antibiotic resistance genes. This integron was different from other qnr-positive sul1-type integrons identified in American and Chinese enterobacterial isolates. In addition, plasmid pQR1 carried another class 1 integron that was identical to In53 from E. coli. The latter integron possessed a series of gene cassettes, including those coding for the extended-spectrum beta-lactamase VEB-1, the rifampin ADP ribosyltransferase ARR-2, and several aminoglycoside resistance markers. This is the first report of plasmid-mediated quinolone resistance in Europe associated with an unknown level of plasmid-mediated multidrug resistance in Enterobacteriaceae.
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Affiliation(s)
- Hedi Mammeri
- Service de Bactériologie-Virologie, Hôpital de Bicêtre, 78 rue du Général Leclerc, 94275 Le Kremlin-Bicêtre cedex, France
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145
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Woodford N, Tierno PM, Young K, Tysall L, Palepou MFI, Ward E, Painter RE, Suber DF, Shungu D, Silver LL, Inglima K, Kornblum J, Livermore DM. Outbreak of Klebsiella pneumoniae producing a new carbapenem-hydrolyzing class A beta-lactamase, KPC-3, in a New York Medical Center. Antimicrob Agents Chemother 2005; 48:4793-9. [PMID: 15561858 PMCID: PMC529220 DOI: 10.1128/aac.48.12.4793-4799.2004] [Citation(s) in RCA: 359] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
From April 2000 to April 2001, 24 patients in intensive care units at Tisch Hospital, New York, N.Y., were infected or colonized by carbapenem-resistant Klebsiella pneumoniae. Pulsed-field gel electrophoresis identified a predominant outbreak strain, but other resistant strains were also recovered. Three representatives of the outbreak strain from separate patients were studied in detail. All were resistant or had reduced susceptibility to imipenem, meropenem, ceftazidime, piperacillin-tazobactam, and gentamicin but remained fully susceptible to tetracycline. PCR amplified a blaKPC allele encoding a novel variant, KPC-3, with a His(272)-->Tyr substitution not found in KPC-2; other carbapenemase genes were absent. In the outbreak strain, KPC-3 was encoded by a 75-kb plasmid, which was transferred in vitro by electroporation and conjugation. The isolates lacked the OmpK35 porin but expressed OmpK36, implying reduced permeability as a cofactor in resistance. This is the third KPC carbapenem-hydrolyzing beta-lactamase variant to have been reported in members of the Enterobacteriaceae, with others reported from the East Coast of the United States. Although producers of these enzymes remain rare, the progress of this enzyme group merits monitoring.
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Affiliation(s)
- Neil Woodford
- Antibiotic resistance Monitoring and Reference Laboratory, Specialist and Reference Microbiology Division-Colindale, Health Protection Agency, London, United Kingdom.
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Riesenfeld CS, Goodman RM, Handelsman J. Uncultured soil bacteria are a reservoir of new antibiotic resistance genes. Environ Microbiol 2004; 6:981-9. [PMID: 15305923 DOI: 10.1111/j.1462-2920.2004.00664.x] [Citation(s) in RCA: 289] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Antibiotic resistance genes are typically isolated by cloning from cultured bacteria or by polymerase chain reaction (PCR) amplification from environmental samples. These methods do not access the potential reservoir of undiscovered antibiotic resistance genes harboured by soil bacteria because most soil bacteria are not cultured readily, and PCR detection of antibiotic resistance genes depends on primers that are based on known genes. To explore this reservoir, we isolated DNA directly from soil samples, cloned the DNA and selected for clones that expressed antibiotic resistance in Escherichia coli. We constructed four libraries that collectively contain 4.1 gigabases of cloned soil DNA. From these and two previously reported libraries, we identified nine clones expressing resistance to aminoglycoside antibiotics and one expressing tetracycline resistance. Based on the predicted amino acid sequences of the resistance genes, the resistance mechanisms include efflux of tetracycline and inactivation of aminoglycoside antibiotics by phosphorylation and acetylation. With one exception, all the sequences are considerably different from previously reported sequences. The results indicate that soil bacteria are a reservoir of antibiotic resistance genes with greater genetic diversity than previously accounted for, and that the diversity can be surveyed by a culture-independent method.
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147
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Wang M, Sahm DF, Jacoby GA, Hooper DC. Emerging plasmid-mediated quinolone resistance associated with the qnr gene in Klebsiella pneumoniae clinical isolates in the United States. Antimicrob Agents Chemother 2004; 48:1295-9. [PMID: 15047532 PMCID: PMC375335 DOI: 10.1128/aac.48.4.1295-1299.2004] [Citation(s) in RCA: 161] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Although quinolone resistance commonly results from chromosomal mutation, recent studies indicate that such resistance can also be transferred on plasmids carrying the gene responsible, qnr. One hundred ten ciprofloxacin-resistant clinical isolates of Klebsiella pneumoniae and Escherichia coli from the United States were screened for the qnr gene by PCR and Southern hybridization of plasmid DNA. Conjugation experiments were done with azide-resistant E. coli J53 as the recipient and selection with azide and sulfonamide, a resistance frequently linked to qnr. EcoRI and BamHI digests of qnr-hybridizing plasmids were subjected to electrophoresis on agarose gels and probed with qnr by Southern hybridization. qnr was detected in 8 (11.1%) of 72 K. pneumoniae strains. These eight positive strains were from six states in the United States. qnr was not found in any of the 38 E. coli strains tested. Quinolone resistance was transferred from seven of the eight probe-positive strains. Transconjugants with qnr-hybridizing plasmids had 32-fold increases in ciprofloxacin MICs relative to E. coli J53. For all eight strains, the sequence of qnr was identical to that originally reported. By size and restriction digests, four plasmids were related to the first-reported plasmid, pMG252, and three were different. Five new qnr plasmids encoded FOX-5 beta-lactamase, as did pMG252, but two others produced SHV-7 extended-spectrum beta-lactamase. Transferable plasmid-mediated quinolone resistance associated with qnr is now widely distributed in quinolone-resistant clinical strains of K. pneumoniae in the United States. Plasmid-determined quinolone resistance contributes to the increasing quinolone resistance of K. pneumoniae isolates and to the linkage previously observed between resistance to quinolones and the latest beta-lactam antibiotics.
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Affiliation(s)
- Minggui Wang
- Division of Infectious Diseases, Massachusetts General Hospital, Boston, Massachusetts 02114, USA
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148
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Wang M, Sahm DF, Jacoby GA, Zhang Y, Hooper DC. Activities of newer quinolones against Escherichia coli and Klebsiella pneumoniae containing the plasmid-mediated quinolone resistance determinant qnr. Antimicrob Agents Chemother 2004; 48:1400-1. [PMID: 15047552 PMCID: PMC375334 DOI: 10.1128/aac.48.4.1400-1401.2004] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Seventeen qnr-containing transconjugants were constructed with azide-resistant Escherichia coli J53 as the recipient, and the MICs of 12 quinolones were tested by agar dilution methods. Sitafloxacin, BAYy3118, and premafloxacin had higher activity in vitro than ciprofloxacin against transconjugants and donors containing qnr. The donors had higher quinolone MICs than the transconjugants.
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Affiliation(s)
- Minggui Wang
- Division of Infectious Diseases, Massachusetts General Hospital, Boston, Massachusetts 02114, USA
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149
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150
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Alvarez M, Tran JH, Chow N, Jacoby GA. Epidemiology of conjugative plasmid-mediated AmpC beta-lactamases in the United States. Antimicrob Agents Chemother 2004; 48:533-7. [PMID: 14742206 PMCID: PMC321551 DOI: 10.1128/aac.48.2.533-537.2004] [Citation(s) in RCA: 137] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A sample of 752 resistant Klebsiella pneumoniae, Klebsiella oxytoca, and Escherichia coli strains from 70 sites in 25 U.S. states and the District of Columbia was examined for transmissibility of resistance to ceftazidime and the nature of the plasmid-mediated beta-lactamase involved. Fifty-nine percent of the K. pneumoniae, 24% of the K. oxytoca, and 44% of the E. coli isolates transferred resistance to ceftazidime. Plasmids encoding AmpC-type beta-lactamase were found in 8.5% of the K. pneumoniae samples, 6.9% of the K. oxytoca samples, and 4% of the E. coli samples, at 20 of the 70 sites and in 10 of the 25 states. ACT-1 beta-lactamase was found at eight sites, four of which were near New York City, where the ACT-1 enzyme was first discovered; ACT-1 beta-lactamase was also found in Massachusetts, Pennsylvania, and Virginia. FOX-5 beta-lactamase was also found at eight sites, mainly in southeastern states but also in New York. Two E. coli strains produced CMY-2, and one K. pneumoniae strain produced DHA-1 beta-lactamase. Pulsed-field gel electrophoresis and plasmid analysis suggested that AmpC-mediated resistance spread both by strain and plasmid dissemination. All AmpC beta-lactamase-containing isolates were resistant to cefoxitin, but so were 11% of strains containing transmissible SHV- and TEM-type extended-spectrum beta-lactamases. A beta-lactamase inhibitor test was helpful in distinguishing the two types of resistance but was not definitive since 24% of clinical isolates producing AmpC beta-lactamase had a positive response to clavulanic acid. Coexistence of AmpC and extended-spectrum beta-lactamases was the main reason for these discrepancies. Plasmid-mediated AmpC-type enzymes are thus responsible for an appreciable fraction of resistance in clinical isolates of Klebsiella spp. and E. coli, are disseminated around the United States, and are not so easily distinguished from other enzymes that mediate resistance to oxyimino-beta-lactams.
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Affiliation(s)
- M Alvarez
- Lahey Clinic, Burlington, and Edith Nourse Rogers Memorial Veterans Hospital, Bedford, Massachusetts, USA
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